1.  Rohan and Sunil separately can complete a work in 8 hours and 4 hours respectively. How much time will they take when working together ?
A. 22/3 hours
B. 11/3 hours
C. 3 hours
D. 2 hours

Answer: Option A

Explanation:

Required time taken to complete the work by both together = x y / x + y

(Here x = 8 and y = 4)

∴ Required time = (8 x 4)/(8 + 4) = 32/12 = 22/3 hours